HOCHENFELLNER F, SORIA M, CORDOBA S, DAVEL G, VIVOT W, RODERO L; Interscience Conference on Antimicrobial Agents and Chemotherapy.

Abstr Intersci Conf Antimicrob Agents Chemother Intersci Conf Antimicrob Agents Chemother. 2000 Sep 17-20; 40: 361.

Instituto Nacional de Enfermedades Infecciosas, Buenos Aires, Argentina

Ergosterol is the major sterol component of the yeast cell membrane and is responsible for maintaining cell integrity and function. It is the target for antifungal agents, principally amphotericin B (AMB), whose mechanism of action is by binding to it. Therefore, yeasts with less content of ergosterol may lead to resistance of this compound. Although, AMB resistance is rare in yeasts, it has been associated in Candida lusitaniae with a reduction of ergosterol in its membrane. C. tropicalis (Ct) has been reported to develop secondary resistance in some cases after repeated exposure to AMB. The aim of this study was to evaluate the possible correlation of the ergosterol content of 19 resistant and susceptible Ct isolates with their MICs for different antifungal agents. Ergosterol was isolated from whole yeast cells by saponification, followed by extraction of nonsaponifiable lipids with heptane and then ergosterol was quantified spectrophotometrically. C. albicans (Ca), C. lusitaniae (Cl), C. haemulonii (Ch) and Trichosporon beigelii (Tb) were used as control strains and to compare different ergosterol content. For Cl and Tb less ergosterol content was observed (0.048-0.044 %ergosterol/wet weight, e%/ww) when compared with Ca or Ch (0.086-0.069 e%/ww). Significative variations (p<0.001) in the percentage of ergosterol was found between the different isolates of Ct (range 0.030-0.071 e%/ww). Our results showed that neither increased resistance to azole drugs nor to AMB in these isolates correlated to altered ergosterol content. This observation has been also reported previously for Ca and fluconazole. Although further studies on isogenic strains of variable resistance must be performed, ergosterol content seemed not to be a determinant factor in AMB resistance development.KEYWORDS: Candida tropicalis; Ergosterol; Resistance

Publication Types:

• Meeting Abstracts

Keywords:

• Amphotericin B
• Antifungal Agents
• Azoles
• Candida
• Candida tropicalis
• Ergosterol
• Fluconazole
• Microbial Sensitivity Tests
• Sterols
• Yeasts

Other ID:

• GWAIDS0010586

UI: 102248084

From Meeting Abstracts